MICR3011 NotesINTRODUCTION

Ancient Greek physicians treated the individual NOT the disease Blood – heart Phlegm – brain Black bile – spleen Yellow bile – liver

Middle Ages New religious doctrines Causes of disease = visitations from divine providence Great plagues attributed to

- Supernatural causes- Influence of undesirable people

Increase trade > greater movement of people Crusades + warfare Growth of cities = crowding + lack of sanitation

- ∴ spread of disease- Result: plague, typhus, leprosy common

Treatments- Bleeding- Purging- Emetics- Diaphoretics- Stimulation of the nervous system

Renaissance Era Treatments: chemists used heavy metals

- Antimony, mercury- Cure = good luck- Harmful

Operations = great risk of infection- Mortality rate 80%- Pus > normal reaction to surgery

Universities = scientific basis for teaching

17th + 18th Centuries Changes in religious, political + cultural doctrines (scientific methods accepted) Surgical + scientific instruments improved

- Eg. Microscope (Anton van Leeuwenhoek) Industrial revolution Scientific exploration of disease; cleanliness + sanitation Hospital-trained experts Common diseases: throat infections, scarlet fever, diphtheria, TB, smallpox 1796 – Jenner’s smallpox vaccine

19th Century Cholera in Europe Public Health Services – sewage systems; reticulated water Register of Births, Deaths & Marriages

Koch- Identified tubercle bacillus & cholera Vibrio- Basic principles of modern diagnostic microbiology

Pasteur- Studied bacteria- Investigated human + animal diseases- Vaccines

Lister- Antisepsis

Last Century World War I 1918 influenza pandemic, cause? Study of infectious diseases & chemotherapy Antimicrobial era

- Dyes, heavy metals- Sulphonamides- Penicillin, streptomycin

Antibiotic resistance developed World War II 1980: Smallpox dead!

- Signs + symptoms distinctive = effective isolation- Patients not contagious during incubation period- No other host for virus- Single serotype- Other poxviruses shared antigens- WHO 10 year global eradication program

Vaccine effective Required only one administration Isolation policy for patients until last scab separated

Today’s problems Antimicrobial resistance Major infection diseases

- HIV/AIDS, tuberculosis + malaria- Keep people in poverty

CLINICAL MICROBIOLOGY

Classical view of Infectious Disease Bacteria classified as commensals OR pathogens If microbe DOES NOT CAUSE DISEASE

- Commensal = normal flora: present at site without causing pathology If microbe SOMETIMES CAUSES DISEASE

- Host = carrier- Host is colonised

If microbe CAUSES DISEASE- Host is infected

Staphylococcus aureus Site as normal flora

- Skin > can spread person-to-person- Nose > colonises nose then spreads to skin- Vagina

Beneficial for- Competition: space + nutrients- Non-pathogenic strains prime immune system

Characteristics of microbe- G+ve clusters- Facultative anaerobe- Complete haemolysis- Coagulase +ve- Capsule- Toxins: exfoliative + enterotoxins (strain specific)

Diseases caused- Pyogenic superficial infections- Surgical wound infections- Osteomyelitis (inflammation of bone)- Systemic blood infections- Impetigo- Ritter’s disease

Escherichia coli Site as normal flora

- Colonises GIT- Most numerous aerobic microbe in large intestine- Can spread anal-oral

Beneficial for- Produces vitamin K for human well-being

Characteristics of microbe- G-ve rod- Enteric = bile tolerant- Facultative aerobe- Lactose fermenter

Diseases caused- Most are ENDOGENOUS- UTIs- Enteric infections- Abdominal wound infection- Pneumonia- Meningitis in neonates- Strain dependent!